An overhead high-voltage electric power distribution conductor may, for a variety of reasons (e.g., pole knocked over, tree fall, pole mounted conductor clamp failure, etc.), become detached or damaged and may fall to the ground while it remains energized, resulting in a ground fault. As the live conductor contacts the ground, it produces electrical arcing. The arcing can ignite flammable materials or vegetation and start a fire, and the flow of electric current may electrocute a person or animal in the vicinity of the fallen conductor. In addition, the zone of personal risk can expand to those standing nearby and to those who touch the victims, such as in an attempt to aid the victims.
Existing electrical protective systems and methods frequently fail to detect that a live conductor has contacted the ground. In favorable situations (e.g., high earth conductivity) where existing methods do detect the disconnected conductor on the ground, they do so only after the conductor has begun arcing on the ground, posing a high risk that a fire has already been ignited or persons nearby have been electrocuted.
Fallen-conductor ground faults, even when visibly dramatic at the site of ground contact, may not produce sufficiently distinguishable and detectable electrical measurement changes at the substation. Furthermore, even when the fault produces currents or signatures that can be detected, the detection and de-energization process may take relatively too long, in the order of 200 ms to several seconds or even minutes (several seconds to minutes is more typical). For every moment a live conductor arcs on the ground, fire or electrocution can occur.